i have a feeling its pretty much as close as you can get to a locked diff, but allowing some slip for slow cornering. I think it allows a very small ammount of differentiation, but as soon as its exceded it locks the wheels solid......Im not sure.

__________________
Ive been described as a vault of usless random knowledge.

In a single spinner diff, there are a series of little gears that allow both axels (wheels) to spin at different speeds. (LSD uses clutches)
With a mini spool, the two axels are locked together, with the carrier.

This means that there is no slip when you drive your car around a corner. Both wheels will always spin at the same time, regardless.

The advantage of a mini spool is that they are dirt cheap, about $120 and can be installed into a stuffed single spinner or LSD diff, provided the axels are still good. Oh, and you can do some seriously crazy burnouts with these diffs.

Te downfall to this type of diff is that the car seems to hop around corners, and tight turns can become annoying. The cars cornering ability is reduced. I imagine that parallel parking would also be annoying. There is increased tyre wear from this setup, as well as more strain on all the drive train components, and things like control arms.
Also, axels my tend to twist severely under heavy loads, which could result in one being snapped. I have been in a car when an axel has snapped during a burnout, and the car was still drivable.

The AutoGuide.com network consists of the largest network of enthusiast-owned enthusiast-operated automotive communities.

AutoGuide.com provides the latest car reviews, auto show coverage, new car prices, and automotive news. The AutoGuide network operates more than 100 automotive forums where our users consult peers for shopping information and advice, and share opinions as a community.